Audio, video and other types of data may be transmitted through a variety of types of networks according to many different protocols. For example, data can be transmitted through a collection of networks usually referred to as the “Internet” using protocols of the Internet protocol suite, such as Internet Protocol (IP) and User Datagram Protocol (UDP). Data is often transmitted through the Internet addressed to a single user. However, it can be addressed to a group of users, commonly known as multicasting. In the case in which the data is addressed to all users it is called broadcasting.
One way of broadcasting data is to use an IP datacasting (IPDC) network. IPDC is a combination of digital broadcast and Internet Protocol. Through such an IP-based broadcasting network, one or more service providers can supply different types of IP services including on-line newspapers, radio, and television. These IP services are organized into one or more media streams in the form of audio, video and/or other types of data. To determine when and where these streams occur, users refer to an electronic service guide (ESG). One example used in digital video broadcasting (DVB) streams is an electronic program guide (EPG). One type of DVB is Digital video broadcasting-handheld (DVB-H), a recently developed technology that increases the capabilities and services available on small handheld devices, such as mobile telephones. The DVB-H is designed to deliver 10 Mbps of data to a battery-powered terminal device.
DVB transport streams deliver compressed audio and video and data to a user via third party delivery networks. Moving Picture Expert Group (MPEG) is a technology by which encoded video, audio, and data within a single program is multiplexed, with other programs, into a transport stream (TS). The TS is a packetised data stream, with fixed length packets, including a header. The individual elements of a program, audio and video, are each carried within packets having a unique packet identification (PID). To enable a receiver device to locate the different elements of a particular program within the TS, Program Specific Information (PSI), which is embedded into the TS, is supplied. In addition, additional Service Information (SI), a set of tables adhering to the MPEG private section syntax, is incorporated into the TS. This enables a receiver device to correctly process the data contained within the TS.
Carousels are intended for the periodic transmission of information over the transport stream (TS). Although the content of a carousel can be changed in response to a request from a destination device, it is more usual for the carousel to be repeated regardless of whether any destination device is active or requesting the carousel data at that moment. A destination device that needs specific data waits until the needed data is retransmitted. Data carousels contain modules of data of unspecified content. Therefore, the destination device must know what to do with the data received. Alternatively, object carousels contain identifiable data objects such as .jpg or .txt files and even the application software needed to use other objects. A directory structure enables a destination device to find an object, to extract and download the object's associated application software, and then to use the object. Data carousels are often used for downloading new system software to destination device whereas an object carousel is typically used for game delivery, shopping services, and electronic service guides (ESG). Both data and object carousels are repeated at periodic intervals though the repetition rate can vary from item to item. For example the ESG for the next hour viewing options may repeat more often than that for the next month.
A number of applications can be included in the same carousel at the same time allowing users the opportunity, e.g., to choose between looking at an ESG and playing an interactive game. Where applications relate to a particular TV program or commercial, it may be desirable for the application to be available to the user for a period of time after the program has ended even though a new application for the next TV program is available. The object carousel generator has to share the overall carousel bandwidth between the various applications being carried at any one time.
Under conventional systems, once a carousel has been generated, changes to programming cannot be made prior to the start of a specified program. As with a printed newspaper, once an ESG has been generated and delivered in a carousel, the content of the ESG cannot be changed. An operator may need to change a program list due to the cancellation of a live event, the unexpected broadcast of a major news event, or the blackout of a broadcast of a sporting event. In the case of a canceled event, the operator may desire to change the live event with a sequence of other programming, such as cartoons, during the two-hour program slot originally set for the live event. Under conventional systems, an operator can change the actual broadcast, but she cannot change the program list received by a mobile terminal. A mobile terminal user can see the cartoons; however, the ESG data still identifies the programming, the cartoons, as the live event.